Solid-state lighting arrays are used for a number of lighting applications. For example, solid-state lighting panels including arrays of solid-state light emitting devices have been used as direct illumination sources in architectural and/or accent lighting. A solid-state light emitting device may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs), which may include inorganic LEDs, which may include semiconductor layers forming p-n junctions and/or organic LEDs (OLEDs), which may include organic light emission layers.
Solid-state lighting devices are also used in lighting fixtures, such as incandescent bulb replacement applications, task lighting, recessed light fixtures and the like. For example, Cree, Inc. produces a variety of recessed downlights, such as the LR-6 and CR-6, which use LEDs for illumination. Solid-state lighting panels are also commonly used as backlights for small liquid crystal display (LCD) screens, such as LCD display screens used in portable electronic devices, and for larger displays, such as LCD television displays.
Some attempts at providing solid-state lighting sources have involved driving an LED or string or group of LEDs using a rectified voltage produced from an AC source. However, because the LEDs generally require a minimum forward voltage to turn on, the LEDs may turn on for only a part of the rectified AC waveform, which may result in visible flickering, may undesirably lower the power factor of the system, and/or may increase resistive loss in the system. Examples of techniques for driving LEDs with a rectified AC waveform are described in U.S. Patent Application Publication No. 2010/0308738. Co-pending U.S. patent application Ser. No. 13/235,103, entitled “Solid-State Lighting Apparatus and Methods Using Energy Storage”, filed Sep. 16, 2011 and Ser. No. 13/405,819, entitled “Solid-State Lighting Apparatus and Methods Using Energy Storage”, filed Feb. 27, 2012, each of which is commonly assigned to the assignee of the present application, describe techniques in which a capacitor or other energy storage device may be used to sustain light output during nulls of the waveform of an AC power source used to power a lighting apparatus. Other attempts at providing AC-driven solid-state lighting sources have involved placing LEDs in an anti-parallel configuration, so that half of the LEDs are driven on each half-cycle of an AC waveform.